It has long been known that the impact energy of an automobile may be dissipated if the automobile hits and crushes a deformable structure or material. Thus, it is known in the art that light weight cement, plastic foam and various fiberous materials may be used to absorb impact energy. Also, various structures such as foam-filled honeycomb arrays have been employed to absorb impact energy by compression.
Moreover, impact energy may be absorbed by the cutting or shearing of relatively rigid energy absorbing structures. For example, as shown in the U.S. Pat. No. to John W. Rich, 3,587,787, a plurality of sheets with intersecting walls may be stacked so that the walls of adjacent sheets cut into one another to dissipate the energy of an incident impact force. It has been found that the energy dissipation of such structures is reduced when a compressive force causes the walls of the sheets to crumple, rather than to cut or shear. Also, the walls of the sheets may expand or contract in response to ambient temperature and moisture conditions and thereby reduce the effectiveness of the energy absorption structure. Moreover, the rigidity and strength of such structures is generally limited and, therefore, the structures may not operate to cut or shear in an optimum manner.
A preferred energy absorber for high-impact energy vehicles such as automobiles or trucks should uniformly and completely crush in order to absorb a maximum impact energy and should provide a force absorption characteristic that increases as the distance travelled by the impacting vehicle increases. The material of such an absorber should provide a high energy absorption per square inch, so that energy absorbing structures may be made as small as possible.
Accordingly, it is an object of the invention to provide an energy absorption apparatus and material that is relatively compact and that operates to uniformly and consistently absorb the impact energies of vehicles such as cars and trucks.
A further object of the invention is to provide an energy absorber that utilizes both shear action and compression to absorb the energy of an impact force.
Another object of the invention is to provide an energy absorber that utilizes the favorable energy absorption characteristic of cutting or shearing lattices and avoids the shearing inefficiencies presently associated with such structures.
A further object of the invention is to provide an energy absorption structure wherein stacked sheets with foam-filled honeycomb cells are caused to cut or shear into one another in response to an applied impact force, so that the energy of the impact is uniformly and efficiently dissipated.